The overarching goal of this methodological, data-driven study is to provide service planners and policymakers with the best available data on the magnitude and sources of racial/ethnic disparities in alcohol and drug abuse treatment services, and information about the consequences of substance disorders in ethnic and racial minority populations in the United States (US). We use four new, large, nationally representative data sets with rich diagnostic and service use information: the National Comorbidity Survey Replication (NCS-R), the National Latino and Asian American Study (NLAAS), the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), and the National Survey on Drug Use and Health (NSDUH). We will provide a comprehensive picture of the extent of substance disorder treatment disparities, the potential sources of intervention to remediate these disparities, and the social and economic burden associated with substance disorders in minorities. Analyses will also provide empirical evidence regarding the mechanisms underlying disparities (e.g., the extent to which disparities reflect the influence of system barriers or state policies);this information will be translated into interventions to reduce disparities.